This is a continuation of work aimed at a clinical, pathologic, and pathophysiologic study of disease of optic nerve head in man and experimental animal models. We have established 5 experimental models of edema of optic nerve head, following 1) ocular hypotony, 2) implantation of intracranial balloon, 3) irradiation of occipital lobe, 4) acute transient elevation of intraocular pressure (8 hrs.), or 5) allergic optic neuritis. The first 4 of these models involves pressure changes in fron or behind the optic disc. In this project, we propose to examine the pathology of the edema of the optic disc in 2 experimental models in monkeys involving vascular embarassment of the optic nerve head: (1) systemic hypertension secondary to modified Goldblatt operation and high cholesterol diet and 2) occlusion of posterior ciliary arteries. In addition, we propose to study the pathologic changes in the optic nerve head in 2 experimental models of subacute or chronic glaucoma: 1) injection of cross-matched sickle red blood cells into anterior chamber of eyes of human patients whose eyes are to be exenterated or enucleated because of orbital neoplasm and 2) to produce chronic elevation of intraocular pressure by repeated photocoagulation of the trabecular meshwork of monkeys. We further propose to study the exchange of interstitial fluid around the optic nerve head by exploring the unusual example of a monkey and dogs with optic pit with or without retinal detachment by introducing horseradish peroxidase, ferritin, and lanthanum nitrate into the carotid circulation, the subarachnoid space, and the vitreous cavity, respectively. The clinical course and pathologic changes of each model will be examined. The disturbance of the circulatory dynamics and/or axoplasmic transport will be investigated in the animal models. With a multidisciplinary approach using method of clinical ophthalmology and experimental pathology including experimental surgery, fluorescein angiography, histopathology, electron microscopy, EM histochemistry, and autoradiography, we propose to study edema and diseases of the optic nerve head.